HP PROCURVE 6208M-SX Installation And Getting Started Manual page 179

Installation and Getting Started Guide
Fixed-Port Architecture
Layer 2 Architecture
When a packet arrives at an HP 6208M-SX switch, a search for the MAC destination address is initiated. If the
MAC destination address is found, the packet's priority is determined. The packet is then forwarded to the
appropriate output port.
Packets that are not located in the address table are forwarded to all other switch ports unless VLANs are
operating on the switch. If the switch is operating with VLANs, then the packet is forwarded only to other ports
within its VLAN.
If the source address of the packet received at the switch is not resident in its address table, or if the source port
of the packet has changed, both the source address and its source port will be programmed into the address
table.
Layer 3 Architecture
When a packet arrives at an HP 9304M, HP 9308M, or HP 6308M-SX routing switch, an address lookup is
initiated.
IP Version 4 Packets
If the IP address is located, then the device performs the following Layer 3 IP operations on the IP packet:
• Decrements the TTL value.
• Checks to see if TTL value is greater than zero. If so, the packet will be forwarded.
• Performs destination MAC address substitution of the next hop router or end station. The source MAC
address will be replaced by the MAC address of the interface.
• Updates the header checksum.
Once Layer 3 operations are completed, the packet's priority is determined, and it is placed in the appropriate
buffer for forwarding to the target output port.
IPX Packets
When an IPX packet is received, the frame type is determined. When the incoming and outgoing frame types are
Ethernet 802.2 or 802.3, the device will perform hardware forwarding:
• If the destination network number is an internal or remote network number.
• If the destination network number is an internal or remote network number, the system will provide network
assistance.
• If the frame type is Ethernet II or Ethernet SNAP, the packet is sent directly to the CPU. The CPU will
increment the transport control count and forward it to its target output port.
Other Protocol Packets
Protocols not supported by the routing switches will be switched at Layer 2.
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